1a large parts of the mine upper- or lower-surface; larva a maggot => 2

1b mine full depth throughout; larva with chitinised head => 4

1c galls, etc. => Tables for all parasites per species

2a frass in green clouds (often visible only after the mine has been opened); mine in the end a blotch overlying the midrib: Scaptomyza flava

2b frass in black string or grains; corridor mine => 3

3a frass in strings; a branching corridor, overlying the midrib; pupation outside the mine: Liriomyza strigata

3b frass in isolated grains; corridor independent of the midrib; pupation within the mine, in a, usually lower-surface, pupal chamber: Chromatomyia horticola

4a mine < 1 cm; larva with thoracic feet and prolegs; the larvae soon leave the mine and start causing window feeding: Plutella xylostella

4b mine larger; larva, without prolegs, mines all its life => 5

5a larva without thoracic feet; mine more or less a corridor: Ceutorhynchus minutus

5b larva with thoracic feet; mine more a blotch: Phyllotreta nemorum